Good morning and welcome back to Generate! After all kinds of wind up, President Trump will sign an executive order today that attacks Obama's climate policies head on. We've got plenty on that below, or just skip the first few items if you're at risk of executive order fatigue, because there's plenty more happening too.

What Trump’s big energy order can and can’t do

The arrival of the executive order is a good time to take stock of Trump's environmental and energy push after two busy months.

So two months into his presidency, how much impact is he having? Easing environmental protections can affect how industry operates, but not necessarily how much it operates. Fossil fuel production is pretty resilient to policy shifts unless they really mess with the underlying market fundamentals. I've got a story over on the Axios stream that explores why rolling back regulations can nudge energy markets but probably can't fundamentally alter them. Check it out here.

Here’s Trump’s plan

The White House walked reporters through the energy and climate order last night.

Why it matters: The order is the clearest sign yet of how aggressively Trump is attacking Obama's regulations on fossil fuel development and coal-fired power generation, which Republicans call economically burdensome.

According to the White House, the order will . . .

Begin the long process of overturning EPA carbon emissions standards for existing and newly constructed power plants.

Scuttle a White House directive that required agencies to consider climate change when reviewing energy, infrastructure and other proposed projects under the National Environmental Policy Act.

Target oil and gas regulations. It directs the EPA and the Interior Department to review rules — clearly with an eye toward rolling them back — including EPA's methane emissions rules for new sources and Interior's rules governing fracking on federal lands.

Hitting the brakes on emissions cuts

One more thing about Trump's climate change order. The Rhodium Group consultancy circulated a research note last night that takes stock of what would happen if everything in the order actually comes to pass.

Their bottom line?

If you compare U.S. greenhouse gas emissions under Trump's policy versus what would happen if Obama's policies stayed intact, they start to diverge beginning in a couple of years. Continued declines under Obama's plan will be replaced with a leveling off under Trump's rollbacks, stabilizing at about 14 percent below 2005 levels.

"That level holds through 2030, however, leaving the U.S. pretty far from the 26-28 [percent] Paris commitment in 2025 and nowhere close to what is considered necessary to meet global climate goals in 2030," they write. However, their analysis adds that if some optimistic assumptions don't hold, the emissions decline could even be reversed and start ticking back up.

Aramco gets a tax cut

Yesterday brought a new wrinkle in what could be the biggest IPO ever. Saudi Arabia is cutting the tax rate for state oil giant Saudi Aramco in preparation for next year's offering. The new rate is 50 percent, down from 85 percent.

"The tax rate is a vital piece in a puzzle the Saudis need to work out with investment bankers to determine the value of Saudi Aramco, the world's biggest producer of crude oil. Current valuation estimates, ranging from $400 billion to $2 trillion, depend on various calculations of the worth of operations, projections of commodity prices, and costs including taxes."

Meeting Africa’s energy needs with renewables

Wind and solar energy can become economically competitive ways to help meet rising energy demand in Africa, but planners need to consider location, location, location, according to new Lawrence Berkeley National Laboratory research.

"[W]ith strategic siting of the renewable energy resource and with more energy trade and grid interconnections between countries, the total system cost can be lower than it would be if countries were to develop their resource in isolation without strategic siting," Ranjit Deshmukh, one of the lead authors, said in a summary of the findings.

Rick Perry goes nuclear

The energy secretary made an unannounced visit to the long-proposed, long-delayed Yucca Mountain nuclear waste repository in Nevada yesterday, a project the Obama administration abandoned that Trump's crew wants to revive.

Perry met with Gov. Brian Sandoval, who opposes the project. Perry said in a statement that they had a "frank and productive discussion."

The Trump administration is asking Congress for $120 million to re-start the licensing process for the decades-old plan that faces stiff opposition from Nevada politicians.

Sandoval said in a statement that he and Perry are longtime friends, but "the storage of high-level waste at Yucca Mountain is not something I am willing to consider."

That's all for today, but please watch the Axios stream for more coverage. I'll be reading other Axios newsletters this morning, because they're really good. You can sign up for all of them here. Thanks for checking out Generate, and your feedback and confidential tips are always welcome at ben@axios.com. See you tomorrow.